Water-in-oil emulsified compositions have good affinity with the skin. In addition, they prevent moisture loss from the skin by forming a film on the skin surface, so that they can protect the skin from drying or give treatment effects to the skin. Owing to such characteristics, they are used extensively for cosmetic compositions. In particular, incorporation of a highly viscous oil agent or a solid one as an oil component in the compositions heightens their skin protecting effects, but is accompanied with a defect such as a sticky feeling upon use.
It is a common practice to increase the water content, use a silicone oil as an oil agent or use powder capable of giving a refreshing feeling upon use in order to provide a refreshing sensation without losing the properties of water-in-oil emulsified compositions. When an oil component containing a solid lipid or an oil agent having a particularly high viscosity is emulsified, however, such a measure is not preferred, because it limits the kinds of surfactants to be used as an emulsifier, or requires a large amount of a surfactant, leading to impairment of the affinity with the skin or sometimes causing irritation to the skin. Moreover, such a highly viscous oil agent becomes a cause for disturbing emulsification in a mixture system intended to give a refreshing feeling by increasing the water content or adding a silicone oil.
Various investigations have been made to obtain a water-in-oil emulsified composition providing a good feeling to skin and having high stability in a water-rich system. For example, in Japanese Patent Application Laid-Open No. Hei 10-139651, described is a water-in-oil emulsified cosmetic composition obtained by emulsifying an amide compound having a melting point of from 0 to 50° C. with a nonionic surfactant having an HLB less than 8. It however cannot attain both a good feeling to skin and a stable emulsion.
In Japanese Patent Application Laid-Open No. 2000-191496, described is a cosmetic composition having a salt made of a sphingosine and a C1-17 organic acid and having a melting point not greater than that of the sphingosine. Here, in order to improve the miscibility with a highly crystallizable sphingosine, a C1-17 organic acid is added to covert the sphingosine into the corresponding cationic salt. This lowers its melting point and facilitates the incorporation of the sphingosine in cosmetic compositions. When the sphingosine salt thus having a reduced melting point is incorporated as a component of an emulsified composition, however, a surfactant must be added to emulsify the salt, so that the resulting composition is not satisfactory from the viewpoint of attaining both good feeling to skin upon use and stability.